The recent growth of smartphone users brought more opportunities to share video imaging and still imaging on the internet, and higher picture quality is required even for smartphone cameras.
As the result, smartphone models have started to feature HDR (High Dynamic Range) function to capture the brilliant colors even when pictures are taken against bright light.
Now, Sony is releasing "IMX214", 13M-pixel stacked CMOS image sensor with the unique SME (Spatially Multiplexed Exposure) -HDR technology.
The image sensor is able to output 13M-pixel HDR at the maximum of 30 frame/s, and stabilized and high resolution HDR imaging can be generated for both video imaging and still imaging.

SME-HDR Technology

The HDR imaging function is one of the effective methods to improve picture quality. The conventional software method to generate one HDR image combining several pictures is not appropriate to capture moving subjects since this method cannot fill the time gap between the respective pictures. Handling several frames is also difficult for high speed video recording which contains big signal processing data.
This time Sony released the IMX214 featuring SME-HDR technology, which is capable of outputting 13M-pixel HDR images. The technology sets two different exposure conditions during shooting and seamlessly performs appropriate image processing to generate optimal images with a wide dynamic range. Therefore, the IMX214 outputs 13M-pixel HDR at 30 frame/s, and brilliant colors are captured even when pictures are taken against bright light for both video imaging and still imaging. (See figure 1.)
As well, this image sensor is capable to handle 4K or 13M-pixel HDR shooting which was not possible in the existing IMX135*2 (featuring BME-HDR function). (See table 1.)

Sony has been adopted back-illuminated structure for shooting in the high sensitivity and low light conditions, and the IMX214 accomplished further improvements of pixel characteristics with the back-illuminated structure. The on-chip lens and photodiode were placed close to each other for better light collecting efficiency compared with the existing back-illuminated structure. Then incident light characteristics and color crosstalk were improved from the existing product with the back-illuminated structure. (See figure 2 and figure 3.)
The better color crosstalk resulted in higher performance in the color-processed SNR, and consequently high-picture quality can be provided even under low light conditions. Also more efficient incident light characteristics enabled the combination with high CRA lens, which contributes to reduce the height of the module, and adopting small F-number lens also allowed to capture brighter images even with short exposure time.

Miniaturization Using Stacked Structure

Cameras mounted on the recent smartphones have increasing demands for high-picture quality and compact size to compete on design of the smartphone itself.
The IMX214 adopts the Sony's specialized stacked structure and accomplished miniaturization while keeping the functions including SME-HDR technology for high-picture quality at the same time. The module size can be cut down and it contributes to the appealing smartphone design.

Figure 1 Comparison of HDR Images

Figure 2 Comparison of Spectral Sensitivity Characteristics

Solid line: IMX214 Dashed line: IMX135

Figure 3 Comparison of Sensitivity Characteristics with Different Incident Angles

Solid line: IMX214 Dashed line: IMX135

Table 1
Device Comparison

Item

IMX135

IMX214

Image size

Diagonal 5.87 mm

←

Total number of pixels

4224 (H) × 3176 (V)
Approx. 13.42M pixels

4224 (H) × 3200 (V)
Approx. 13.51M pixels

Number of active pixels

4208 (H) × 3120 (V)
Approx. 13.13M pixels

←

Fabrication process

Back-illuminated process

Back-illuminated process
+ reduced height structure

Unit cell size

1.12 µm (H) × 1.12 µm (V)

←

Output format

MIPI 4, 2 Lane

←

Control communication interface

I2C

←

Power supply
specifications

Analog

2.7 +0.2/-0.1 V

←

Digital

1.05 ± 0.1 V

1.0 +0.15/-0.1 V

I/O

1.8 ± 0.1 V

←

Input clock frequency

6 to 27 MHz

←

Signal processing function within sensors

Spot pixel compensation

✔

←

Noise reduction

✔

←

HDR

✔

←

HDR video
specification

Full

Not supported

30 frame/s

4K

Not supported

30 frame/s

1080p

30 frame/s

60 frame/s

*Sony reserves the right to change products and specifications without prior notice.

VOICE

The IMX214 targets that even smartphones can capture clearer still imaging and video imaging, and all project members put our best effort starting from the design to the manufacturing phases.
Please try this image sensor evolving Sony's unique HDR technology and do not miss the opportunity to make a new imaging experience that Sony is striving for.